Method for achieving a specific temperature behavior of adjusting elements operating in dependence on temperature and an adjusting element operating in dependence on temperature

ABSTRACT

A method for achieving a specific temperature behavior of adjusting elements, operating in dependence on temperature, of valves or thermostatic apparatus is disclosed, and also an adjusting element, operating in dependence on temperature, of valves or thermostatic apparatus. Such adjusting elements work in many cases by means of pressure from a pressure chamber, which is provided with a liquid-gas filling. This filling is in many cases toxic or environmentally harmful, in order to achieve satisfactorily the desired temperature behavior. In order to be able to use also non-toxic and environmentally harmless substances, the pressure chamber is filled with a zeotropic mixture of at least two substances. The ratio of component substances is set in dependence on the desired temperature behavior.

The invention relates to a method for achieving a specific temperaturebehaviour of adjusting elements of valves or thermostatic apparatus,which elements operate in dependence on temperature, and an adjustingelement operating in dependence on temperature.

One class of temperature-dependent adjusting elements, as disclosed, forexample, in U.S. Pat. No. 5,044,170, has a pressure chamber which isfilled partially with fluid and partially with gas, the gas-filled partof the pressure chamber containing at least in part the gaseous phase ofthe liquid. If the temperature to which the pressure chamber is exposedthen changes, the temperature of the liquid-gas filling also changes,and consequently the pressure in the pressure chamber. The change inpressure can be detected either by measuring techniques or can be useddirectly to operate an actuator, for instance, to displace a diaphragm.If the liquid comprises a pure substance, the temperature behaviour ofthe adjusting element can be predicted relatively easily, because withpure substances there is a simple correlation between pressure andtemperature. This correlation can be represented in apressure-temperature graph by a single line. The adjusting element inthe form of a signal transducer between the temperature and the desiredoutput signal, for example, a displacement movement or the actuation ofan electrical switch, accordingly has exactly the same simplecorrelation, which can also be easily predicted in advance.

But many of these pure substances, which are used for a number of commonapplications, are toxic or at least greatly harmful to the environment.Provided that the adjusting elements are sound and operational, thisgives no further cause for concern, but in the event of damage,considerable threats to health or the environment are therefore posed.Disposal of such adjusting elements also becomes especially difficult.By virtue of their filling, the adjusting elements are then frequentlyclassed as special-grade waste.

The invention is based on the problem of achieving a desiredtemperature-dependent adjustment without using toxic or ecologicallyharmful substances.

This problem is solved by a method for adjusting the temperaturebehaviour of adjusting elements which operate in dependence ontemperature of valves or thermostatic apparatus which have an actuatingelement acted on by pressure in a pressure chamber, in that a zeotropicmixture is produced from at least two substances, the mixture isintroduced into the pressure chamber and the ratio of componentsubstances is adjusted in dependence on the desired temperaturebehaviour.

One is therefore no longer restricted to the use of a pure substance,which, as stated, is in many cases toxic or ecologically harmful. It isnow possible to use substances that are not harmful to the environmentand are non-toxic. The desired temperature behaviour is then achievedfirstly by using not just one, but several substances and, secondly, bysetting the ratio of these component substances so that the desiredtemperature behaviour is achieved. In most cases the adjusting elementsdo not need to be changed mechanically at all. By suitable selection ofthe substances and by suitable setting of the ratio of these componentsubstances, it is possible to simulate the desired temperaturebehaviour. It should be noted, however, that when using severalsubstances as the filling, the relationship between the temperature andthe pressure is generally no longer a simple theoretical one. Forzeotropic mixtures, however, the pressure is a clear function oftemperature, the ratio of components and the density of the substance.Normally, the boiling point line of multi-substance mixtures differsfrom the condensing point line. Between the two lines there exists aregion in a pressure-temperature graph in which a part of the liquid hasalready gone over into the gaseous phase, but another part is still inthe liquid phase. It is in this region that the resultingpressure-temperature line is found; this can be determinedtheoretically, but only with considerable effort. According to theinvention, however, there is no need to measure the pressure. On thecontrary, the effects caused on a change in temperature are useddirectly as a measure to determine whether the desired temperaturebehaviour has been achieved or not. It is thus possible to achieve withthe desired accuracy a simple correlation between the temperature andthe signal of the adjusting element, that is, for example, between thetemperature and the distance travelled by the adjusting element,although the correlation between the temperature and the pressure is notquite so simple. With a zeotropic mixture, the gaseous phase can have adifferent ratio of components from the liquid phase. The use of azeotropic mixture means that one is no longer restricted to certainratios of components. The ratio of components per se can nevertheless bevery accurately set, because specific amounts of substance areintroduced into the pressure chamber, without having to pay heed towhether the substance is in a liquid or gaseous form.

The ratio of components is preferably varied until the desiredtemperature behaviour is obtained.

It is especially preferred for the ratio of components to be adaptedindividually to each separate adjusting element. In this manner it ispossible to compensate for mechanical inaccuracies which may arise, forexample, during manufacture.

A further substance, which is substantially insoluble in the mixture andremains gaseous in the desired temperature range, is preferably added tothe mixture. The addition of such a substance enables the pressure inthe gaseous phase to be increased, so that the adjusting element isbiassed. The output signal of the adjusting element, that is, forexample, the displacement movement, is thereby shifted withoutsubstantial change in the pressure-signal conversion function takingplace. An additive term is merely added to this function.

The gaseous substance is preferably nitrogen, helium or carbon dioxide.Helium can be used at the same time for testing the seal of such anadjusting element.

The problem is also solved by an adjusting element, operating independence on temperature, of valves or thermostatic apparatus in whichan actuating element is in pressure connection with a pressure chamber,the pressure chamber containing a zeotropic mixture of at least twosubstances, which are present partially in liquid form and partially ingaseous form.

One is no longer restricted to a single pure substance when charging thepressure chamber. On the contrary, as stated above, a mixture of atleast two substances can now be used, the desired temperature behaviourbeing determined essentially by the ratio of component substances, ofwhich there are at least two. Here, non-toxic and environmentallyharmless substances can be used, which do not pose problems duringsubsequent disposal of such an adjusting element. The choice ofcomponent ratio enables the effect of the adjusting element, that is,its output signal, to be set to the required extent in dependence on thetemperature. Here, even temperature-dependent signal curves that werenot possible with the previously used pure substances can be set. Whenusing a zeotropic mixture, one is not restricted to certain ratios ofcomponents in which azeotropy is achieved.

The zeotropic mixture preferably consists of substances fromecologically harmless classes of chemical compounds. Damage to theenvironment is thus dramatically curtailed.

The following compounds in particular can be used:

halogen-containing compounds,

halogen-carbon-containing compounds orhalogen-hydrogen-carbon-containing compounds,

fluorine-carbon-containing compounds orfluorine-oxygen-carbon-containing compounds,

chlorine-carbon-containing compounds orchlorine-oxygen-carbon-containing compounds,

hydrocarbons,

hydrogen-oxygen-carbon compounds

aliphatic hydrocarbons,

a selection of the following substances R22, R23, R32, R123, R123a,R124, R125, R134, R134a, R141b, R142b, R143a, R152a, methane, ethane,propane, butane, isobutane, ethylene, propylene, propylene,dimethylether,

the substances R22 and R152a,

any combination of the above-mentioned substances.

The invention is described below with reference to preferred embodimentsin conjunction with the drawings, in which

FIG. 1 shows a valve having an actuating element controlled independence on temperature,

FIG. 2 shows a thermostatic switch having an actuating member controlledin dependence on temperature,

FIG. 3 shows a diagrammatic correlation between pressure and temperaturefor a pure substance,

FIG. 4 shows the diagrammatic correlation between pressure, temperatureand the ratio of components for a zeotropic mixture, and

FIG. 5 shows the correlation between the pressure and ratio ofcomponents at different temperatures.

A valve 1 controlled in dependence on temperature comprises a housing 2with a valve inlet 3 and a valve outlet 4, which are connected to oneanother by way of a flow channel 5. In the flow channel 5 there isarranged a valve seat 6 against which a closure element 7 can be causedto bear. The closure element 7 is held by a spring 8 in the closedposition and is acted upon by a diaphragm 9 in the direction away fromthe valve seat 6. The spring 8 bears against a supporting disc 10, theposition of which can be changed by means of an adjusting screw 11. Thebias of the spring 8 and consequently the basic setting of the valve 1can thereby be changed. The diaphragm 9 is connected on the side remotefrom the closure element 7 by way of a tubular connection 12, whichhere, for example, can be in the form of a capillary tube, to atemperature sensor 13, or more accurately speaking, the pressure chamber14 thereof. The pressure chamber 14 is filled partly with liquid 15 andpartly with gas 16. When the temperature around the temperature sensor13 changes, the pressure conditions in the pressure chamber 14 change.This change in pressure is transmitted by way of the tubular connection12 to the side of the diaphragm 9 remote from the closure element 7. Thepressure exerts a force on the diaphragm 9. Depending on the magnitudeof this force, the diaphragm 9 moves the closure element 7 against theforce of the spring 8 to a greater or lesser extent away from the valveseat 6. The degree of opening of the valve 1 is thus set in dependenceon temperature.

FIG. 2 shows a thermostatic switch 20 having a temperature sensor 21which has a pressure chamber 22. This is again partly filled with aliquid 23 and partly with a gas 24. The pressure in the pressure chamber22 acts on the end face of a bellows 26, to the other side of whichthere is secured a tappet 27. The tappet 27 is held, for a predeterminedtemperature, in equilibrium by two springs 28, 29.

Secured to the tappet 27 are two arms 30, 31, between which there isarranged an operating lever 32 of a switch 33 having two normally opencontacts 34, 35 and one normally closed contact 36. In the neutralposition of the tappet 27, the normally closed contact 36 does not toucheither of the two normally open contacts 34, 35. If the pressure in thepressure chamber 22 rises, however, the tappet 27 is moved upwards bymeans of the end face of the bellows 26. The operating lever 32 ispressed upwards by the lower arm 30 so that the normally closed contact36 connects with the upper normally open contact 34. If the pressure inthe pressure chamber 22 drops, the tappet 27 moves in the oppositedirection and the normally closed contact 36 is brought into contactwith the other normally open contact 35.

Valves and thermostatic apparatus of this kind are known. The filling ofthe pressure chamber 14, 22 in that case consisted of a pure substance,the pressure-temperature dependency of which is illustrated in FIG. 3.As can be seen, to each temperature T there is exactly one pressure Pand vice versa. With this starting point, the temperature behaviour ofthe actuating element can be calculated, and therefore predicted,relatively accurately. As mentioned initially, the pure substances have,however, the disadvantage that they are in many cases toxic orecologically harmful.

To fill the pressure chamber 14, 22, use is no longer made of a puresubstance but a mixture of at least two substances. The correlationbetween pressure and temperature is now more complex. It dependsadditionally on the ratio of components and on the density of thesubstances. For two substances this is illustrated diagrammatically inFIG. 4. In this illustration, the pressure is plotted upwards, thetemperature to the right and rear and the ratio of components to theleft and rear. Only for the outer boundaries is there a curve such asthat illustrated in FIG. 3. These are the curves UBHC₁ and KAC₂. Thesecurves in turn, however, represent the curves for pure substances, sincethey refer to the component ratio of 1:0 and 0:1.

Almost all component ratios between these two extreme values have thepeculiarity that the boiling point line and the condensing point line donot coincide. The boiling point line is represented by the curve BLA,whilst the condensing point line is represented by AVWB. At a pressureabove the boiling point line a full transition to the liquid phase iseffected, at a pressure below the condensing point line a transition tothe gaseous phase is effected. Between these there is an indeterminatestate, that is, part of the mixture is gaseous and part of the mixtureis fluid. It is accordingly difficult to predict the gas pressure in thepressure chamber 14, 22. Both the boiling point line and the condensingpoint line are very heavily dependent on the ratio of components. Thisstate of affairs is plotted in FIG. 5 for different temperatures T1-T5assumed to be constant. Here, T1>T2>T3>T4>T5. In principle, FIG. 5illustrates different intersections each at constant temperature in theP-M plane according to FIG. 4, that is, for example, intersections asapparent from the areas UM-KNU and LLAVWB respectively in FIG. 4. Bothillustrations are, of course, only diagrammatic and are not able toreproduce exact values.

The desired temperature behaviour can now be set by varying the ratio ofcomponents. Here, a pressure-temperature dependency can be produced asillustrated, for example, by the line NWSFM in FIG. 4. One can clearlysee that by changing the ratio of components this pressure-temperaturefunction can be altered. The peaks for different such curves are plottedalong the line C₁ SC₂. With certain constituents, only a limitedadjustment of the temperature behaviour is possible, of course. One is,however relatively free as regards the choice of substances to make upthe mixture.

The ratio of components can also be further altered as the pressurechambers 14, 22 are being filled in order to adapt the temperaturebehaviour to individual apparatuses.

All ecologically harmless classes of chemical compounds can beconsidered as substances that can be used for the mixture. Inparticular, halogen-containing compounds can be used, for examplehalogen-oxygen-carbon containing compounds, such asfluorine-carbon-containing compounds orfluorine-oxygen-carbon-containing compounds, orchlorine-carbon-containing compounds orchlorine-oxygen-carbon-containing compounds. Preferred are alsochlorine-fluorine-carbon-containing orchlorine-fluorine-oxygen-carbon-containing compounds and hydrocarbons.Hydrogen-oxygen-carbon compounds can also be used, of course, and alsoaliphatic hydrocarbons. A selection of the following substances can alsobe used: R22, R23, R32, R123, R123a, R124, R125, R134, R134a, R141b,R142b, R143a, R15a, methane, ethane, propane, butane, isobutane,ethylene, propylane, propylene, dimethylether. A mixture of thesubstances R22 and R152a is especially advantageous. The ratio ofcomponents can in principle be chosen at random, until the desiredtemperature behaviour has been reached. Zeotropic mixtures in particularcan be used. The filling can additionally have added to it a gas, suchas helium, nitrogen or carbon dioxide, in order to shift the dependencytowards the P-axis (pressure axis) without altering the curve of thefunction per se.

We claim:
 1. A method for achieving a specific temperature behaviour ofadjusting elements, operating in dependence on temperature, of valves orthermostatic apparatus which have an actuating element acted on bypressure in a pressure chamber in which method a zeotropic mixture, fromat least two component substances, is introduced into the pressurechamber, which mixture has a boiling point line and a condensing pointline which do not coincide, between which lines is an indeterminatestate, where part of the mixture is gaseous and part of the mixture isfluid, where an area for operation is limited by the boiling point lineand the condensing point line, which area for operation is changed byvariation of the ratio of components in order to obtain the desiredtemperature behaviour.
 2. A method according to claim 1, in which theratio of component substances is varied until the desired temperaturebehavior is obtained.
 3. A method according to claim 2, in which theratio of component substances is adapted individually to each separateadjusting element.
 4. A method according to claim 1, in which a furthersubstance, which is substantially insoluble in the mixture and remainsgaseous in a desired temperature range, is added to the mixture.
 5. Amethod according to claim 4, in which the gaseous substance is selectedfrom the group of nitrogen, helium and carbon dioxide.
 6. An adjustingelement, operating in dependence on temperature, of valves orthermostatic apparatus in which an actuating element is in pressureconnection with a pressure chamber, the pressure chamber containing azeotropic mixture of at least two component substances, which mixturehas a boiling point line and a condensing point line which do notcoincide, between said lines is an indeterminate state where part of themixture is gaseous and part of the mixture is fluid, where an area foroperation is limited by the boiling point line and the condensing pointline, which area for operation is changed by variation of the ratio ofcomponents in order to obtain the desired temperature behavior.
 7. Anadjusting element according to claim 6, in which the zeotropic mixtureconsists of substances from ecologically harmless classes of chemicalcompounds.
 8. An adjusting element according to claim 6, in which thezeotropic mixture consists of halogen-containing compounds.
 9. Anadjusting element according to claim 6, in which the zeotropic mixtureconsists of halogen-carbon-containing compounds orhalogen-hydrogen-carbon-containing compounds.
 10. An adjusting elementaccording to claim 6, in which the zeotropic mixture consists offluorine-carbon-containing compounds orfluorine-oxygen-carbon-containing compounds.
 11. An adjusting elementaccording to claim 6, in which the zeotropic mixture consists ofchlorine-carbon-containing compounds orchlorine-oxygen-carbon-containing compounds.
 12. An adjusting elementaccording to claim 6, in which the zeotropic mixture consists ofchlorine-fluorine-carbon-containing compounds orchlorine-fluorine-oxygen-carbon-containing compounds.
 13. An adjustingelement according to claim 6, in which the zeotropic mixture consists ofhydrocarbons.
 14. An adjusting element according to claim 6, in whichthe zeotropic mixture consists of hydrogen-oxygen-carbon compounds. 15.An adjusting element according to claim 6, in which the zeotropicmixture consists of aliphatic hydrocarbons.
 16. An adjusting elementaccording to claim 6, in which the zeotropic mixture is selected fromthe group of the following substances: R22, R23, R32, R123, R123a, R124,R125, R134, R134a, R141b, R142b, R143a, R152a, methane, ethane, propane,butane, isobutane, ethylene, propylane, propylene, dimethylether.
 17. Anadjusting element according to claim 6, in which the zeotropic mixtureconsists of the substances R22 and R152a.